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Monthly changes in sedimentation and sediment properties were studied for three different culture treatments: sea cucumber monoculture (Mc), sea cucumber and scallop polyculture (Ps-c) and scallop monoculture (Ms). Results indicated that the survival rate of sea cucumber was significantly higher in Ps-c cultures than in Mc cultures. Sea cucumber yield was 69.6% higher in Ps-c culture than in Mc culture. No significant differences in body weight and scallop shell length were found between Ps-c and Ms cultures. The mean sedimentation rate of total particulate matter (TPM) was 72.2 g/(m2 d) in Ps-c cultures, with a maximum of 119.7 g/(m2 d), which was markedly higher than that of Mc (mean value). Sedimentation rates of organic matter (OM), total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in Ps-c cultures were also significantly higher than those in Mc cultures. TOC and TN contents of sediment increased rapidly in the first 5 months in Ms cultures and remained at a high level. TOC and TN contents in Mc and Ps-c cultures decreased during sea cucumber feeding seasons and increased during sea cucumber dormancy periods (summer and winter). The study demonstrates that co-culture of sea cucumber and scallop in earthen ponds is an alternative way to alleviate nutrient loads and improve water quality in coastal aquaculture systems. Moreover, it provides the additional benefit of an increased sea cucumber yield. 相似文献
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Mônica L. Botter-Carvalho Paulo V.V.C. Carvalho Ana Paula M.C. Valença Paulo J.P. Santos 《Marine pollution bulletin》2014
A field experiment to assess the effects of continuous nutrient addition on the macrobenthic community was carried out on an estuarine mudflat on the northeast coast of Brazil. The experiment began on 5 October 2005 and ended on 8 February 2006. Macrofauna was compared at approximately four-week intervals in triplicate plots with three levels (Control – C, Low Dose – LD and High Dose – HD) of weekly fertilizer additions for 17 weeks. Inorganic fertilizer (N–P–K) was applied on nine randomly defined quadrangular plots (4 m2 each). All measurements were calculated from species abundances. Multivariate analyses as well as the univariate indices (richness, abundance and Shannon–Wiener index) showed statistically significant differences between the enriched and control areas during the period of the experiment. The expected gradual response based on the succession model of Pearson and Rosenberg was not observed. The nutrient doses used were high enough to cause severe decreases in abundance, richness and evenness, and an increase in dominance. 相似文献
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混合氮源对扁藻与金藻共培养和单种培养生长的影响 总被引：3，自引：0，他引：3
采用均匀设计,研究了硝酸钠(NO3-N)、尿素(NH2-N)和硫酸铵(NH4-N)3种氮源对亚心形扁藻(Platymonas subcordiformis)与球等鞭金藻(Isochrysis galbana)共培养和单种培养生长的影响。结果表明,不同氮源对扁藻与金藻在不同培养方式下的生长均存在显著差异(P<0.05)。共培养时,硝酸钠质量浓度对扁藻和金藻的总细胞密度(Yt)和最终细胞密度的体积比(Yr)没有影响,尿素质量浓度对Yt有正调节作用,而硫酸铵质量浓度对Yt有负调节作用、对Yr有正调节作用。当培养液中NH2-N质量浓度为21.01 mg/L,扁藻和金藻接种体积比(Xv)为14.15时,Yt最大(1 508.9×104个/mL);当NH4-N质量浓度、Xv分别为21.00 mg/L和14.15时,Yr最大,为87.46。单种培养金藻时,硝酸钠略优于尿素,2种氮源对其生长均有正调节作用,而硫酸铵起负调节作用。当培养液中加21.01 mg/L的NO3-N和NH2-N时,金藻的细胞密度达到最大值(862.6×104个/mL);不同氮源对扁藻生长的调节作用与金藻相反,当扁藻接种密度为4.6×104个/mL,培养液中NH4-N质量浓度为21.00mg/L时,扁藻细胞密度达到102.2×104个/mL,其值最大。 相似文献
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This study aimed at investigating the photosynthetic pigment accumulation and some growth indices of cowpea, maize and tomato in response to interspecific and intraspecific competition stress. The study was carried out under a screen-house to minimize extraneous factors such as pests and rodents using a randomized complete block design(RCBD). Seeds of cowpea, maize and tomato were collected from the Department of Crop Production and Protection, Faculty of Agriculture,Obafemi Awolowo University, Ile Ife, Osun state, Nigeria. These seeds were planted at a depth of about 3 mm below the soil. The seeds were sown at the rate of six seeds per pot in the monoculture, while in the pots designed for the mixed culture of maize and cowpea, maize and tomato, cowpea and tomato, three seeds of each plant were sown. Two seeds of each plant were sown in the pots with the three crops. The treatments were then supplied with 500 m L of tap water in the morning and in the evening respectively until the seedlings become fully established. The photosynthetic pigments were determined spectrophotometrically with three replicates. Plant growth indices were determined according to Hunts(1978) using leaf area and dry matter data collected at four and six weeks after planting. Statistical analysis was performed using statistical analytical software SAS version 9.2. The results indicated that photosynthetic pigments accumulation(Chlorophyll a, b and carotenoid) in maize(15.98, 23.92 and 44.72 μM), Chlorophyll b and carotenoid in tomato plants(12.48 and 1,178.7μM) in the sole stands were more than the mixed culture of maize with cowpea and tomato(7.195, 14.74 and 0.00 μM).Also, total Chlorophyll in maize(1,127.8 μM), Chlorophyll a and total Chlorophyll in tomato(3.95 and 1,317.5 μM) in the mixed culture were more than in the sole culture of maize(1,030.9 μM) and tomato plants(-9.40 and 546.3 μM). The different photosynthetic pigments accumulated in cowpea were greatly enhanced in the mixed culture than in the sole culture.All the photosynthetic pigments of maize, cowpea and tomato in all the treatments analysed in this study were significantly different at P0.05. Plant growth indices such as net assimilation rate, relative growth rate, crop growth rate and tissue water contents of these plants had higher value in the intercropped than the check crop(sole). These plant growth indices were significantly different to one another at P0.05. This study concluded that competition for shared resources in the mixed culture of tomato, maize and cowpea enhanced growth and accumulation of photosynthetic pigments. 相似文献
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通过盆栽试验,研究浓度为300×10-6 mol·kg-1的丁香酚对小麦（Triticum aestivum）间作蚕豆（Vicia faba）、单作小麦和单作蚕豆根系形态的影响,以期探讨通过间作弱化化感抑制作用的可能性和机理,为间作群体的化感物质调控提供理论依据。结果表明：丁香酚对单作小麦和间作蚕豆单株根鲜重、干重、根长都有抑制效应,但对间作小麦和单作蚕豆的单株根鲜重、干重、单株根长有促进效应。具体表现在间作复合群体中,经丁香酚处理后,小麦的单株根鲜重、干重、体积以及根长较单作有明显的增加,同时单株蚕豆根鲜重、干重、体积以及根长较单作显著减少,说明小麦间作蚕豆能有效缓解小麦根际丁香酚的累积,同时产生它感作用,对蚕豆根系生长产生明显的抑制效应。 相似文献
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探究引起银鲫在不同养殖模式下的形质差异原因及形质饰变途径和机制,进而揭示养殖模式致其改变生存对策的内在逻辑,对于指导银鲫养殖模式的改进与优化具重要现实意义。随机选取池塘生态主养模式(M1)和池塘生态套养模式(M2)下经7个月养殖的异育银鲫夏花苗种各70尾为研究对象,采用主成分分析和判别分析方法,系统开展了两种池养模式下异育银鲫形质差异研究,结果表明:(1)池养期间两实验群体的生长速度总体上呈M2>M1,在21项生物学表型性状中,M2实验群体显著大于M1实验群体的为L1 (体长)、L4 (头宽)、L11 (肛后体长)和NM (净体质量)(P<0.05);(2)所涉20项形质评价性状中, M1、M2实验群体间具显著差异(P<0.05)的高达16项,聚类分析也指示两者间的欧式距离已达到显著水平(P<0.05),即M1、M2实验群体已在形质特征上出现显著分化;(3)经主成分分析,提取到的5个特征值均大于1的主成分,其累... 相似文献
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